Clinical significance of dynamical network indices of surface electromyography for reticular neuromuscular control assessment

Abstract

Background: There is currently no objective and accurate clinical assessment of reticular neuromuscular control in healthy subjects or patients with upper motor neuron injury. As a result, clinical dysfunctions of neuromuscular control could just be semi-quantified, efficacies and mechanisms of various therapies for neuromuscular control improving are difficult to verify.

Methods: Fourteen healthy participants were required to maintain standing balance in the kinetostatics model of Gusu Constraint Standing Training (GCST). A backward and upward constraint force was applied to their trunk at 0°, 20° and 25°, respectively. The multiplex recurrence network (MRN) was applied to analyze the surface electromyography signals of 16 muscles of bilateral lower limbs during the tests. Different levels of MRN network indices were utilized to assess reticular neuromuscular control.

Results: Compared with the 0° test, the MRN indices related to muscle coordination of bilateral lower limbs, of unilateral lower limb and of inter limbs showed significant increase when participants stood in 20° and 25° tests (P < 0.05). The indices related to muscle contribution of gluteal, anterior thigh and calf muscles significantly increased when participants stood in 20° and 25° tests (P < 0.05).

Conclusions: This study applied the dynamical network indices of MRN to analyze the changes of neuromuscular control of lower limbs of healthy participants in the kinetostatics model of GCST. Results showed that the overall coordination of lower limb muscles would be significantly enhanced during performing GCST, partly by the enhancement of neuromuscular control of single lower limb, and partly by the enhancement of joint control across lower limbs. In particular, the muscles in buttocks, anterior thighs and calves played a more important role in the overall coordination, and their involvement was significantly increased. The MRN could provide details of control at the bilateral lower limbs, unilateral lower limb, inter limbs, and single muscle levels, and has the potential to be a new tool for assessing the reticular neuromuscular control. Trial registration ChiCTR2100055090.

Keywords: Gusu Constraint Standing Training; Lower limbs; Motor model; Multiplex recurrence network; Reticular neuromuscular control; Surface electromyography.

Fig. 1

One participant performed standing tests under three conditions. A: 0° test; B: 20° test; C: 25° test

Fig. 2

Schematic of the MRN construction and the indices extraction

Fig. 3

The interlayer mutual information matrix of MRN for a representative participant under different standing conditions. L: left limb; R: right limb

Fig. 4

Network indices of bilateral lower limbs ($\stackrel{-}{x}$ ± SD). * Significant difference between two test conditions

Fig. 5

Network indices of unilateral lower limb ($\stackrel{-}{x}$ ± SD). * Significant difference between two test conditions; ^† Significant difference between two sides

Fig. 6

Statistical results of inter-limb I ($\stackrel{-}{x}$ ± SD). * Significant difference between two test conditions

Fig. 7

Ranking of muscle-related I of participants in three conditions